A blast in the central Damascus district of Marjeh on Tuesday killed at least 13 people, Syrian state television reported, a day after a Prime Minister Wael al-Halqi survived a bomb attack elsewhere in the capital.

"The number of casualties in the cowardly terrorist blast targeting the commercial and historic centre of Damascus in the Marjeh district rose to 13 martyrs and more than 70 injured," state television reported, citing the interior ministry.

The Syrian Observatory for Human Rights reported "14 dead, including nine civilians and five members of the security forces, in a car bomb attack near the old interior ministry headquarters."

The toll could rise further because a number of the wounded were in critical condition, the monitoring group said.

"Internationally-financed and -supported terrorism committed a terrible massacre against civilians in the commercial and historic centre of Damascus," state television reported, citing an official source.

Official channels broadcast footage showing smoke billowing over the site of the explosion, which blew out the windows of nearby cars, knocking off the bumpers some and starting fires.

Uniformed and armed plainclothes security forces could be seen running near the scene, as residents fled.

Several mutilated bodies could be seen lying in the street, and at least one body wrapped in a white sheet was laid out alongside an ambulance.

Fire engines were at the scene with firefighters battling several blazes.

"What mistake have we committed? I was going to work. Look at the bodies. Is this the freedom they want?" a bystander said to state media.

The attack came a day after a blast in the Mazzeh neighbourhood of the capital targeting Halqi.

The car bomb, which exploded as his convoy passed through the upscale neighbourhood, killed one of his bodyguards and five other people, according to the Observatory.

The blast, apparently detonated by remote control, took place in the well-secured Mazzeh district, which is home to politicians, embassies, government offices and intelligence facilities.

Halqi, who was appointed prime minister in August 2012 after his predecessor Riad Hijab defected to the opposition, is the latest in a growing list of regime officials to be targeted for assassination.

In July 2012, a suicide bomb attack killed Syria's defence minister and deputy defence minister and seriously wounded the interior minister.

Damascus has seen a wave of major bombings in recent weeks, including on April 9, when a massive blast in the centre of the city killed at least 15 people.